Radeon's ROCm 1.5 OpenCL Support Is Working Out Better

With the recent release of ROCm 1.5 followed by the ROCm OpenCL runtime finally being open-sourced, here are some fresh OpenCL benchmarks of this newer Radeon graphics compute stack.

Back when testing ROCm 1.4 OpenCL back in January, its performance was in some instances coming up slower than the older OpenCL stack bundled within the AMDGPU-PRO driver. Fortunately, with the testing of the latest ROCm OpenCL binary packages, the OpenCL support appears much better as about to be shown in our fresh CL benchmark results.

As of writing, ROCm still only has complete OpenCL 1.2 run-time and compiler support but some elements of OpenCL 2.0+ including a compatible kernel language implementation. Hopefully in the not too distant future will be complete OpenCL 2.0~2.2 support. At least though this OpenCL stack is much better off than the Clover OpenCL Gallium3D state tracker that hasn't received much attention from AMD in quite a while.

For this testing I was using Ubuntu 16.04.2 LTS, one of the supported platforms for ROCm and where binary packages are available.

While ROCm OpenCL is now open-source, it's not yet in a desirable state for wide adoption on the Linux desktop or servers. ROCm still depends upon unmerged kernel changes, so the ROCm Ubuntu packages in AMD's repository ship with its own 4.9-based kernel. Additionally, it has its own fork of LLVM/Clang/LLD. Hopefully the remaining items will be merged soon and other issues cleaned up so it will be easier to deploy and make use of ROCm across a spectrum of Linux systems.

Just for clarification, the ROCm OpenCL stack is independent of Mesa and does not tie into it or Gallium3D. Disappointing some will be that this ROCm OpenCL stack currently only supports Fiji / Polaris graphics processors and newer.

For some fresh ROCm OpenCL benchmarking I compared the performance of its latest 1.5 packages to that of AMDGPU-PRO 17.10. These tests happened from the Intel Xeon E3-1280 v5 + Sapphire Radeon RX 470 OC system. These OpenCL tests were run via the Phoronix Test Suite.